The immune system is an intricately designed defense mechanism. It acts to neutralise infectious bacteria, viruses and generally protect the body from disease.

However, when the immune system is too sensitive, it can react to normally harmless substances in the environment. This is an allergic reaction.

The substances that cause an allergic reaction are called allergens. These can be biological (pollens, dust, bacteria), chemical (rubber, nickel, isocyanates in spray paint) or physical (heat, light, electromagnetic radiation).

So what’s going on in the body?

The body’s first response to an allergen is to release antibodies. These antibodies stimulate cells in the blood to release histamine.

Histamine affects lots of different body tissues. As we saw in the post Peptics Ulcers and Medical Treatment, there are histamine receptors in the stomach that release gastric acid. However, there are also histamine receptors in the skin, lungs, sinuses, and certain blood cells. This means that there are many possible responses to release of histamine:

Skin: a rash or itch.

Lungs: narrowing of airways. This can cause wheezing and difficulty breathing.

Sinuses: increased mucous production. This can cause a runny nose or productive cough.

Blood: widens blood vessels. This causes a rapid drop in blood pressure which can lead to shock.

Some of these reactions can be useful when fighting off a real infection and trying to get bacteria out of the body. For example, the widened blood vessels allow faster transport of white blood cells to attack a source of infection.

In addition to this, increased mucous production protects areas such as the lungs from bacterial invasion. Mucous is used to protect internal body tissue: in the lungs, it is a protective layer between bacteria-containing air and body tissue. Increased mucous production is intended to trap and expel bacteria from the body (when it is coughed out).

How serious are allergies?

The severity of an allergic reaction ranges from mild, such as hayfever, to severe. Anaphylaxis is an extreme all-body allergic reaction with symptoms such as difficulty breathing, itchiness, nausea and dizziness. It can have fatal consequences if not treated immediately by a professional.

If the allergic reaction is from a bee sting, carefully scrape the stinger off the skin with a credit card. DO NOT use tweezers: squeezing the stinger releases more venom.

If the person has emergency medicine on hand, help the person to take or inject it. Avoid oral medication such as pills if the person is having difficulty breathing.

If there is no concern about suspected head/neck/back/leg injury, take these steps to prevent shock:

Have the person lie down

Raise the person’s feet 30cm or so off the ground

Cover them with a coat or blanket

Treating allergic reactions

Severe reactions: Adrenaline is the body’s natural histamine inhibitor, blocking the histamine receptors. An adrenaline dose is often carried by a person who has anaphylaxis. When given to a person in anaphylactic shock, the adrenaline should block the symptoms of an allergic reaction. This can be life-saving.

Mild reactions: Anti-histamines are often prescribed for people with mild allergies. These drugs also block histamine receptors, but particularly target the receptors in the skin and sinuses to prevent rashes and a runny nose.

Immunotherapy

Doctors may use ‘allergy shots’ to prevent allergic reactions. The idea is to inject your body with very small doses of whatever it is you are allergic to. This should slowly change your body’s reaction to this allergen. The process is a slow one and may take up to 5 years.

Have you ever heard that a little bit of knowledge is a dangerous thing? When we look at the history of treating stomach peptic ulcers, the importance of thoroughly understanding a medical condition in order to treat it effectively becomes obvious.

So, what is a peptic ulcer?

It’s a hole in the mucous membrane of the stomach. This hole allows the gastric acid in your stomach to reach the stomach lining, irritating it and causing dull or burning pain*. If left untreated, peptic ulcers can result in severe bleeding and even death. However, there have been effective treatments around for ulcers since the 1970’s.

When pharmaceutical companies first looked at developing medicines for treating stomach ulcers, they were thought to be caused by stress, spicy food or alcohol. Nowadays, we know otherwise, but these factors can make the symptoms of a peptic ulcer worse.

It was understood then, and still is today, that gastric acid makes peptic ulcers worse. So the first type of medication developed for treating peptic ulcers were H2 Histamine antagonists.

Histamine, a hormone, can cause the release of gastric acid from parietal cells in the stomach. This happens when histamine interacts with a special type of receptor on these cells called the H2 receptor. H2 Histamine antagonists such as cimetidine (trade name Tagamet) bind to H2 receptors without stimulating gastric acid release, blocking Histamine from binding and so decreasing the amount of gastric acid produced in the stomach.

Cimetidine, marketed in the UK in 1976, was the first really effective antiulcer drug. No longer was it necessary to swallow large amounts of antacids (bases such as sodium bicarbonate or calcium carbonate) to try to neutralize gastric acid. No longer was surgery the only way to get rid of a peptic ulcer.

As effective as drugs like cimetidine were, a new and superior class of medication to treat ulcers was developed in the 1980’s. These new drugs are called Proton Pump Inhibitors (PPI’s).

All gastric acid production is done in the parietal cells through an enzyme complex called a proton pump. A Proton Pump Inhibitor such as omeprazole (trade name Losec) is a weak base. When it reaches the highly acidic openings to the parietal cells, it is ionized to an active form and binds irreversibly to the proton pump by forming a covalent bond to a free Histidine residue. This prevents formation of hydrochloric acid, the main component of gastric acid.

Drugs like cimetidine prevent histamine from stimulating the proton pump to produce hydrochloric acid, blocking one stimulatory pathway. But there are other ways to activate the proton pump. Drugs like omeprazole prevent the proton pump from producing any hydrochloric acid. This is clearly a better way to reduce the amount of gastric acid in the stomach near a peptic ulcer.

However, one of the puzzling aspects of stomach ulcers is their tendency to reoccur after finishing a course of medication.

This was explained to be because of a microorganism called H. pylori in the stomach. Scientific evidence has implicated H. pylori infection as one of the main causes of peptic ulcers. H. pylori are associated with inflammation of the stomach, as they can produce cytotoxins that have been specifically linked to peptic ulceration**.

Treatment of H. pylori infection is done using antibiotics. Combination therapy of a PPI and at least two bacterial agents has been shown to eradicate H. pylori in over 90% of ulcers and significantly reduce the likelihood of reoccurrence of a peptic ulcer***.

So from an approach aimed at preventing aggravation of an ulcer by reducing the amount of gastric acid in the stomach, medicine is now trying to kill off one of the main cause of ulcers: H. pylori.

It is worth mentioning briefly that the other main cause of ulcers is non-steroidal anti-inflammatories (NSAIDS) such as asprin. NSAIDS prevent a special enzyme called COX-1 from working. This enzyme produces a chemical messenger to stop acid secretion and protect the walls of the stomach.

Please note: This information is not designed to help anyone make self-diagnoses. There is a reason our doctors train for at least 6 years before they are allowed to practice medicine. The human body is wonderfully made and a complex biological environment. Stomach pain can be an indicator of many different medical problems.